"Project D: Core Resources" represents the physical and administrative core of the Program Project. Major expenses related to general infrastructure support are included In this section in order to centralize the support activities on which all of the other projects rely. The major items that represent the bulk of the budget for this section include the service contracts on the electron microscopes, systems management and maintenance of computers, upkeep and development of miscellaneous equipment, and our share of the maintenance of equipment that is shared with other investigators in Donner Lab who are not participants in the Program Project. General research on improvement of the efficiency and quality of data collection is carried out in the context of the CORE. Certain expenses that might be considered part of the basic administrative infrastructure, and which are nevertheless charged as direct costs (such as telephone service, space and electricity), are budgeted in the Core Resources. The Core Resources budget also includes costs for the fraction of personnel effort associated the infrastructure maintenance and with the scientific management of the Core facilities as well as the Program Project as a whole.